1. Field of the Invention.
The present invention relates to a device for leveling and/or metering a layer of liquid or viscous coating medium onto a moving background. With direct application of the operating medium, the moving background is a material web, preferably a paper or cardboard web. With indirect application, it is the surface of a transfer element which transfers the liquid or viscous medium onto the material web.
2. Description of the Related Art.
When leveling and/or metering the coating medium layer on the background, precise positioning of the leveling and/or metering element against the background is of utmost importance. If the leveling and/or metering element is positioned too far from the background during operation, it will not remove the desired amount of coating medium from the background, resulting in a total coating weight that is too high. In extreme instances, the leveling and/or metering element may not even be in a position to smooth the coating medium layer to the desired extent. If, in contrast, the leveling and/or metering element is positioned too closely to the background, it will remove an excessive amount of coating medium, resulting in an overall coating weight that is too low. In extreme instances, this may even result in damage to the material web, the transfer element or the leveling and/or metering element.
Because of the aforementioned reasons, precisely adjustable power components must be utilized with conventional leveling and/or metering devices. However, such precisely adjustable power components are expensive with regard to purchase and maintenance.
Therefore, it was suggested in European patent document no. EP O 418 476 B1 to provide a lever mechanism between the power transfer device acting upon the doctor blade (=leveling and/or metering element) and the power components, which would reduce the regulating distance of the applicable power component into a correspondingly shorter regulating distance of the power transfer device. However, the suggested lever mechanisms permit only a relatively small reduction so that relatively precisely adjustable power components would still have to be used.